1. Technical Field
The present invention relates to semiconductor processing, and more particularly to methods for achieving high resolution resist structures for template formation for directed self-assembly (DSA) processing.
2. Description of the Related Art
Directed self assembly (DSA) has emerged as a useful tool in semiconductor processing. DSA includes providing two materials and polymerizing them to concurrently form the materials into separate polymer regions. By providing physical guides, mandrels or templates, the polymers can be formed into useful structures, e.g., parallel lines and the like. DSA may be employed, e.g., to form interconnect lines, spacers and/or contacts.
DSA typically requires high-resolution templates to ensure proper formation of the DSA structures. However, present techniques yield large inaccurate resist features, which cannot form high resolution mandrels. Further, metal lift-off processes from resist features require metal deposition onto a neutral material layer leading to high defect levels and high line edge roughness (LER). Employing e-beam resists to form resist patterns on top of the neutral material layer is not a manufacturable lithographic technique useful for device production.
With these techniques or potential techniques, the height and profile of the resist tends to be poor at presently achievable and useful line widths, and these techniques may result in damage to the neutral material layer needed for the formation of DSA films and other structures.